The present invention relates generally to dynamoelectric machines and, more particularly, to new and improved dynamoelectric machine lubrication systems and methods of assembling the same.
In dynamoelectric machines such as electric motors (and some generators and alternators), sleeve bearing systems are used wherein an oil supply or reservoir is contained in the vicinity of a bearing. In some cases, this oil is stored within the interstices of lubricant storage material. The lubricant storage material may be, for example, pieces of wool felt, fibers of chopped materials (such as, for example, materials of the type shown and described in U.S. Pat. No. 2,966,459; or materials of the type that are disclosed in Whitt U.S. Pat. Nos. 3,894,956 and 3,907,690). An example of a wool felt oil storage system is shown in my own prior U.S. Pat. No. 3,235,317 which issued Feb. 15, 1966.
Some motors are provided with sealed bearing housings so designed that it is difficult, if not impossible, to supply additional oil to the bearing system once the motor has been put into use. Obviously, with this type of motor, the useful life of the motor is related to the life of the bearing, and therefore is usually limited to the time required for the amount of oil stored in the oil system to decrease to a critical quantity such that the rate of feed of oil into the bearing clearance will have decreased to a point so that there will be insufficient lubricant to prevent a rapid increase in bearing friction and wear. One practical measure of when friction and wear has become excessive is when friction becomes so great that it prevents the motor from starting, or when wear causes a loss of the magnetic air gap; or when increased noise levels resulting from wear cannot be tolerated.
It will be understood that many motors are provided with means that permit periodic re-oiling of the lubrication system. Such an arrangement is illustrated, for example, in my above-mentioned U.S. Pat. No. 3,235,317. However, motors are not always re-oiled as frequently as they should be once they have been put into service. Moreover, even if motors are re-oiled at the manufacturer's recommended time intervals, the longer periods of time between re-oiling usually are a substantial convenience to an end user. The period of time (for a given motor) between re-oiling is also related to the time required for the amount of oil stored in the system to decrease to a critical quantity such that the rate of feed of oil into the bearing clearance has decreased to a value that it will not prevent a rapid increase in bearing wear and friction.
It should now be understood that it would be generally desirable to provide new and improved bearing lubrication systems, as well as methods of manufacturing and assembling the same, such that it will take relatively longer before the stored oil is depleted to a critical quantity.
In aplications where motors will be re-oiled at specified maintenance intervals; any improvements in bearing systems that diminish the amount of oil loss from a bearing system may provide the further advantage of permitting a reduction in the volume required for oil storage, or a reduction in the amount of oil provided initially in the bearing and lubrication system. This is of obvious benefit from the standpoint of conservation of motor lubricants and raw materials from which such lubricants are made.
Much work has been done heretofore to minimize loss of oil from bearing and lubrication systems of dynamoelectric machines. For example, substantial amounts of work have been done in connection with providing improved oil flingers or flingers which will be more efficient in returning oil to the oil retention system or oil storage system after the oil has migrated along the length of the shaft and out along the bearing journal and to the end of the bearing. Stokke et al U.S. Pat. No. 3,793,543, assigned to the assignee of this application, is evidence of some of the work that has been done in this particular area.